1. Field of the Technology
The present technology relates to an image forming apparatus having a print function by an electrophotographic system, including a copier, a printer, a facsimile device, and the like, and a toner supply container used therefor.
2. Description of the Prior Art
An image forming apparatus using an electrostatic photographic system includes steps of charging, exposure, development, transfer, peeling, cleaning, charge erasing, and fixing. In the step of forming an image, for example, a surface of a photoreceptor drum which is driven to rotate is uniformly charged by a charger, and the charged surface of the photoreceptor drum is then exposed to laser light, thus forming an electrostatic latent image thereon. Subsequently, toner is electrostatically attached to the electrostatic latent image on the surface of the photoreceptor drum to develop, followed by forming a toner image on the photoreceptor drum. Then, the toner image on the photoreceptor drum is transferred onto a transfer material by a transfer apparatus, and the toner image on the transfer material is fixed by a heating and fixing apparatus. Moreover, residual transfer toner on the surface of the photoreceptor drum is removed by a cleaning apparatus and collected in a predetermined collecting portion, as well as residual electric charges on the surface of the photoreceptor drum after cleaning are removed by a charge erasing device to perform the following image formation.
As the photoreceptor drum, a photoreceptor drum to which an organic photoconductor (OPC) is applied as a photoconductive layer is generally used, and a corona charger is used as the charger for applying electric charges to the surface of the photoreceptor drum in many cases.
In one corona charger, a very thin conductive tungsten wire is covered with a conductive shield case in a peripheral portion except for a portion opposite to the photoreceptor drum, and a high voltage is applied to the tungsten wire itself so that corona discharge is caused to charge the photoreceptor drum. Besides, in another corona charger, a saw-toothed discharging electrode having many sharp projections arranged in line is disposed instead of the tungsten wire for corona discharge and the photoreceptor drum is charged by the corona discharge from the sharp projections. The corona charger is also used for the charge erasing device, the transfer apparatus, and the like, in addition to charge of the photoreceptor drum.
In the corona charger, when dirt adheres to a tungsten wire, a saw-toothed discharging electrode, or the like, a discharge function only in the corresponding part is deteriorated, thus making it impossible to charge the photoreceptor drum uniformly. When such charging irregularities are caused, image defects, such as a black streak in an obtained image, occur.
Furthermore, a prior technology for solving a problem about dirt on a needle-like electrode as described above is disclosed, for example, in Patent Literature 1. According to the technology disclosed in Patent Literature 1 (Japanese Patent Application Laid-Open Hei 7 No. 43990), the needle-like electrode is sandwiched, from both sides, by a cleaning member made of a pair of rollers supported rotatably and the cleaning member is relatively moved with respect to the needle-like electrode to thereby remove dirt adhering to the needle-like electrode.
Although this method is useful as a method for refreshing the needle-like electrode in which charging irregularities are caused, it is not to prevent dirt from adhering to a discharge electrode of a corona charger, and it is necessary to clean the corona charger frequently in order to obtain excellent image quality at all times.